1. Field of The Invention
The invention relates to a shaped charge carrier assembly of the type utilized to perforate an oil or gas well. The invention particularly pertains to the manner in which the shaped charge is held in place relative to the carrier, and to the manner in which the detonating cord is assembled with the carrier and the shaped charges.
2. Description of The Prior Art
Perforating guns commonly used in wire line service operations for perforating an oil or gas well typically include a carrier having a plurality of shaped charges attached thereto with a detonating cord assembled with the carrier and engaged with the shaped charges for detonating them. This assembly may be housed in a hollow cylindrical housing, or in some cases, the carrier assembly itself is lowered into the well without a protective housing. If a protective housing is not utilized, a dome-shaped cover may be placed over the forward face of the shaped charge to assure that an appropriate minimum standoff distance is maintained between the charge and the wellbore.
Recently, the assignee of the present invention has developed an improved shaped charge carrier made of sheet metal which has openings formed therein along with resilient tab means adjacent those openings. The shaped charges may be assembled with the carrier by merely pressing them into the openings. The resilient tab means forcibly grip the shaped charges and hold them in place within the carrier.
This prior art device is shown and described in detail in U.S. Pat. No. 4,655,138 filed Sept. 17, 1984, for SHAPED CHARGE CARRIER ASSEMBLY, which is assigned to the assignee of the present invention. The structure shown in FIGS. 1-7 and 13 of U.S. Pat. No. 4,655,138 a part of the prior art. That device utilizes two diagonally opposed resilient tabs which engage a threaded outer surface of the charge for holding each shaped charge in place. It is noted that Application Ser. No. 651,201 itself is not a part of the prior art. Applicants are merely referring to FIGS. 1-7 and 13 of that prior application as a convenient means of describing the structure shown in those figures, which structure is a part of the prior art. Any disclosure of U.S. Pat. No. 4,655,138 which is not illustrated in FIGS. 1-7 and 13 is not conceded to be a part of the prior art.
Additionally, the prior art has included a number of flat strip type carriers having shaped charges placed through openings in the carriers and having a detonating cord threaded through openings of the carriers for engagement with each of the shaped charges. Such devices are shown for example in U.S. Pat. No. 4,312,273 to Camp; U. S. Pat. No. 3,078,797 to Blair; U. S. Pat. No. 2,760,434 to Ruth; and U. S. Pat. No. 2,756,677 to McCullough.
Although the recently developed flexible tab type holding means disclosed in Application Ser. No. 651,201 has provided a significant improvement in shaped charge carrier assemblies, the present invention provides an improved version of that flexible tab type holding means. Further, the improved flexible tab type holding means of the present invention is particularly adapted for use in a flat strip type carrier assembly and provides a uniquely efficient manner of assembling the strip type carrier, the shaped charges and the detonating cord.